I am getting an intermittent high transmission temp warning light on my 99 XJR w/ 93k when I park on a downward slope. On Sunday I drove six blocks, parked on moderate incline, had breakfast, came out 45 min later and on start up got the high temp warning and the car was in failsafe. I disconnected the battery, put the car in neutral and started the car. I had to drive 200 miles and did so with no issues. This morning I ran down the street half a mile to the store, parked on an incline and right before I turned the car off the warning popped up and then immediately disappeared. I turned the car off then restarted and had no light. After doing some reading I am thinking it might be the sensor in the transmission harness. Does anyone have any other ideas?

 

As a non-educated guess, both times you had the high temperature warning you had parked on a slope. Maybe check the fluid level as a simple first step?

 

Transmission cooler fluid level or faulty sensor

 

Those were my thoughts. I was also thinking possibly a faulty battery? I am not sure the slope is coincidental or not. It hasn't happened when driving up or down hills.

 

Info for you.

bob

 

Thank you sir. I appreciate your expertise. This car is new to me and the previous owner just informed me that the trans was replaced 3k ago with a 50k used unit so oil and filter is new and I have not been able to observe any leaks. Don't know if that would change the diagnosis at all but thought it might be relevant.

 

I got a "gearbox temperature high" warning when my alternator was on the way out. When I checked the charging voltage at the time (on the battery terminals) it was only 12.5 volts (13.6 - 14.2 is normal). So, before suspecting any other fault, check the charging voltage when the engine is idling.

 

Took the XJR into a trans shop and they replaced the leaking electrical connect motorcar man alerted me too and topped off the fluid which was 4 qts low. The scanner was showing them a PO705 range sensor circuit and P0710 Trans temp circuit codes. Live data scan showed the cpu was thinking the trans temp would increase 80 degrees when shifter into park or neutral. He concluded the trans is operating well but I have an electrical gremlin. Possible thoughts are the previously suggested electrical harness in the trans, alternator, or remnants of a previously installed "autoguard" alarm. Thelocks act funny when I use the key fob and I occasionally get an unusual chirp when I lock the doors using the fob. Any other thoughts or experience would be appreciated?

 

This is PRECISELY what Motorcarman (deserves a really BIG thanks! ) posted in the TSB covering this issue:
https://www.jaguarforums.com/forum/a...0-oil-temp.pdf

When not in D or R, the PDU proportedly grabbs the temp of the COOLANT to display to the Technician, supposedly for lack of pins on the TCM to detect all the other shifter positions other than D and R. HUH!?! What were the ZF and IDS/SDD engineers and programmers thinking !?!

After all, the ECM and TCM are on the exact same communiction bus, one of them is detecting P and/or N because you cannot start the car unless in one of those two positions, and when not in park switching OFF the ignition an alarm sounds. The PDU has access to ALL the sensors on ALL the modules.

That is exactly what the communication busses are for, exchanging data parameters of sensors that are connected directly to other modules ... Idiot programmers
As an industry control systems professional, I find that TSB rationalization of the problem in 1998 rather disgusting even for 24+ year old premium luxury performance vehicles that has a dozen + computer modules in them, all linked by three or four communication busses.
Remeber, the "next new thing" is technologically obsolete 6-9 months after it is released to the market.

 

this is a nag1 feature with all egs versions. 96 s-class or 2015 jeep always the same behavior 🤷‍♂️

 

I hate nags, and I especially dislike useless nags.

 

The 2003 XJR I recently purchased would report "Transmission Temp High" mostly when the car was first powered on. It also would not start in park sometimes...only in neutral. I adjusted the park switch on the side of the shifter and have not had that warning since nor the not starting in park problem. Plenty of other issues though! Not sure if this applies to your car or not.

As I said to my pal who was ribbing me for having to fix a number of issues with my third 200 VDP after I first bought it, once you get everything sorted out, they are very reliable and great to drive. I have the two pictured on my signature line which rarely have an issue. It's the 2003 XJR that I'm in process of fixing everything....

 

The 722.6 gearbox has a temp sensor as part of the CONDUCTOR PLATE and replacing that part is probably all that is required.

One of my XKR 2000MY convertibles displayed HIGH GEARBOX TEMP on and off for a few weeks.

New conductor plate kit from FCP Euro, a few quarts of SHELL 134 and everything back to normal.